Gear case



Feb. 26, 1957 MCCARTHY ETAL GEAR CASE 2 Sheets-Sheet 1 Filed Feb. 1, 1955 1! I l! 1 'I A Jo/m/ HINCEC1IQ5Y BY I A/ORMAN P/sK W M7: ":HH'

ATTORNEYS Feb. 26, 1957 J, MCCARTHY ETAL GEAR CASE '2 Sheets-Sheet 2 Filed Feb. 1, 1955 INVENTO L/o 4 M CARTHY op/vA/v IP/S/f Anazazvm United States Patent O GEAR CASE John H. McCarthy and Norman E. Risk, Peoria, 111., assignors to Caterpillar Tractor Co., Peoria, IIL, a corporation of California Application February 1, 1955, Serial No. 485,544 4 Claims. (Cl. 74-606) This invention relates to sealing a fluid containing compartment from an adjacent dry compartment and particularly to such sealing as applied to compartments that are fabricated or built up of separate parts welded together as distinguished from compartments formed as castings.

A common form of tractor frame construction comprises a unitary drive containing housing comprising a central oil lubricated compartment for the engine driven bevel gear and pinion and a dry compartment adjacent each side of said central compartment to contain the steering clutches and brakes of the tractor power train which must of necessity be kept free of oil to insure proper functioning of the clutches and brakes.

A large iron casting has been employed for the unitary drive containing housing wherein the central compartment is completely oil tight. Large castings of this type are objectionable since cast iron is quite brittle and subject to breakage upon striking of objects during operation of the tractor. Furthermore, cast iron undergoes metal strain when it is subjected to wide variations in temperature as frequently occurs in extremely hot or cold climates in which tractors are called upon to operate. Such strain frequently results in cracking of the frame castings.

Many of the objections to the cast unitary housing can be eliminated by providing a fabricated unit composed essentially of sheet or plate steel rigidly secured together as by welding to provide a strong but relatively light construction. Fabricated cases, however, have the inherent disadvantage that it is almost impossible to completely isolate the wet compartment from the adjacent dry compartments since limited access to the interior of the case during construction prevents the formation of continuous weld beads at all junctions of the various plates making up the case.

It is the object of this invention, therefore, to provide means for efiectively sealing the compartments of a fabricated gear case by arresting the fiow of fluid between abutting edges and faces of various plates of the case.

In the drawings:

Fig. 1 is a view in perspective, with parts broken away, of a tractor frame and unitary drive containing housing in which this invention is employed;

Fig. 2 is a view in perspective of part of the unitary housing during one stage of assembly;

Fig. 3 is a fragmentary view in perspective, with parts broken away, taken from the direction indicated by the line III-III in Fig. I;

Fig. 4 is an enlarged detail in section taken along the line IV-IV in Fig. 3;

Fig. 5 is a fragmentary view in perspective, with parts broken away, taken from the direction indicated by the line VV in Fig. 1;

Fig. 6 is an enlarged detail in section taken on the line VI-VI of Fig. 5;

Fig. 7 is a fragmentary view in perspective disclosing the manner of securing the top plate of the housing to the rear plate thereof; and

, 2,782,656 Patented Feb. 26, 1957 Fig. 8 is. a fragmentary view in cross-section showing means securing the bottom of the housing to the rear plate thereof.

The main tractor frame or body to which this invention is particularly directed and upon which the engine and operators station ,(not shown) are mounted, is composed essentially of two main parts. One of these parts comprises a rear case 10 adapted to contain the drive mechanism and steering clutch mechanisms and which is formed essentially of a plurality of steel plates welded together into a unitary rigid structure to provide lightness and strength. The other part comprises spaced side members 12 rigidly secured as by welding to the front of the rear case for supporting the tractor engine.

Case 10 comprises a front plate 13 having a relatively large aperture 13' formed therein (Fig. 5) to receive the tractor transmission output shaft and bevel pinion. A top plate 14 secured, as 'by welding, to the rear face of plate 13 and to the top edge of a rear plate 16 is provided with apertures. 15 and 18 to permit access to the interior of the case for purposes of repair and assembly of parts within the case. Rear plate 16 is provided with a central inspection hole 17 through which the transmission shaft may be extended to power rear mounted auxiliary equipment.

A bottom plate comprising a fiat front portion 21 has an upwardly inclined rear portion 22 to provide space for bearing blocks 23 for receiving spindles to support tractor drive members, not shown.

The interior of case 10 is divided by a pair of spaced vertical, longitudinally extending partition plates 25 into a central so-called wet compartment which houses the driving bevel gear, and is adapted to contain lubricant for such gear, and a pair of outer so-called dry clutch and brake compartments. Suitable bosses and pads 32 are provided on the partition walls to form bearings or supports forthe various brake and steering clutch mechanisms.

To assemble case 10, front plate 13 is secured to the bottom plate 2122 by forming a continuous weld head 33 between the front face of plate 13 and the top face of the bottom plate. The fnont plate is then secured to top plate 14 by forming a continuous weld bead 34 between the rear face of plate 13 and the top face of plate 14. Top plate 14 is secured to rear plate 16 by forming a continuous weld bead 35 between the rear edge of plate 14 and the top edge of plate .16. The inclined rear portion 22 of the bottom plate is secured to rear plate 16 by forming a continuous weld bead 36 (Figs. 1 and 8) between the lower face of bottom plate and the front face of plate 16. Partition plates 25 are next positioned within the boX-like structure thus formed and are secured in place by forming continuous weld beads between the outer faces of the partition plates and the inner faces of the front, top, rear, and bottom plates of the case, as for example, by continuous weld beads 38. Since the outer ends of the partitioned box-like structure thus far formed are open as disclosed in Fig. 2, the outer comparttnents are readily accessible and continuous weld beads can easily be formed inside these outer compartments at the junction of the top and bottom plates with the front and rear plates of the case as indicated at 40, 41, 42 and 43.

A side plate 48 is next welded to each side of case 10 by forming continuous weld beads 44, 45, 46 and 47 between the outer face of each side plate and the front, top, and rear plates respectively of the case. Each side plate 48 is provided with an aperture 49 to permit passage therethrough of shafts, not shown, for driving the gears contained within unitary sealed final drive housings, not shown, secured as by welding to the outer faces of side plates 48.

It is highly desirable to provide maximum strength for the case by welding the central or wet compartment at the unction of the inner faces of partition walls 25 with the front, rear, top and bottom plates. However, as is best illustrated in Fig. 1, it is impossible to form continuous oil-tight weld beads at these locations due to the limited access to the interior of the central compartment through aperture 18 and for this reason, intermittent spot welds are used at these locations.

Similarly, due to limited access to the interior of the outer steering clutch compartments through apertures and 49, intermittent welds must of necessity be pro-' vided between the inner faces of the side plates and the front, top, rear and bottom plates of the case in lieu of the preferred oil-tight continuous weld beads.

As is best shown in Fig. 3, the intermittent welds on the interior of the central wet compartment are not effective to seal the channels inherently formed between the top edges of partition walls 25 and the bottom face of top plate 14, the front edge of the top plate and the rear face of front plate 13, as well as between the rear'face of the front plate and the front edges of partition walls 25. Thus oil from the central compartment can enter these channels as indicated by arrows in Fig. 3. Normally oil in these channels will follow the continuous weld beads to the intersection of top plate 14 with side plates 43 and will spill into the dry compartments from between the various intermittent welds therein. According to the present invention, this flow of oil from the central compartment to the outer compartments is arrested by forming holes in front plate 13 outwardly of partition walls as indicated at 53 so that these holes intersect the above-described channels. Thus weld dams 54 can be formed in holes 53 to block communication of oil between the wet compartment and the dry compartments. As is best disclosed in Fig. 4, circular plugs 55 may be welded in place in holes 53 after formation of the dams to provide a flush front face on the case.

Similarly, as shown in Fig. 5, oil from the central compartment can enter outwardly extending channels between 1' the bottom edge of front plate 13 and the upper face of bottom plate 21 as indicated by arrows whereby oil in these channels can spill into the dry compartments along the intermittent weld lines in the dry compartments.

These channels are blocked by providing weld dams 60 i in holes formed through bottom plate 21 outwardly of the partition walls 25 intersecting said channels. Circular plugs 62 can be inserted and welded into these holes as previously described to provide a flush bottom plate on case 10.

As is best disclosed in Figs. 1 and 7, the flow of oil from the central compartment to the dry compartments between the top edge of rear plate 16 and the bottom face of top plate 14 in a channel bounded by continuous welds 35 and 42 is blocked by providing semi-circular notches 63 in the rear edge of the top plate outwardly of partition walls 25 so that continuous weld 35 joins Weld 42 to form an Oil-light dam within said notches.

As is best disclosed in Fig. 8, the flow dam at the junction of the inclined portion 22 of the bottom plate with the rear plate 16 is continuous from partition walls 25 to the outer edges of the bottom and rear plates due to the angularity of the rear edge of the bottom plate with respect to the inner face of rear plate 16 thus forming a V-shaped groove which is completely filled by weld bead 41.

With the present invention, it is possible to provide a light-weight, high-strength fabricated box-like case with a central wet compartment effectively sealed from adjacent dry compartments.

We claim:

1. A case comprising a plurality of plates joined by welding and comprising a fluid containing compartment and adjacent dry compartments, means to arrest the flow of fluid between abutting faces of said'plates from the fluid containing compartment to the dry compartments, said means comprising an aperture through one of the abutting plates exteriorly of said fluid containing compartment and a fluid-tight dam in said aperture joining said plate.

2. A case comprising a plurality of plates joined by welding to form a box-like structure, a plurality of separate compartments within said case, at least one of said compartments being fluid containing, means to prevent communication of fluid from one compartment to an adjacent compartment between the abutting faces of plates forming said compartments comprising an impervious dam formed in an aperture in one of said abutting plates and joining the other of said abutting plates.

3. A case comprising a plurality of plates joined by welding to form a box-like structure, a plurality of separate compartments within said case, at least one of said compartments being for reception of fluid, means to pre vent communication of fluid from one compartment to an adjacent compartment between the abutting faces of plates forming said compartments, said means comprising an impervious dam joining both abutting plates over the full width of abutment of said plates.

4. In a case comprising a plurality of plates joined by welding to form a box-like structure, and having a plurality of separate compartments, at least one of said compartments being for reception of fluid, means to prevent communication of fluid from one compartment to an adjacent compartment between the abutting faces of plates forming said compartments comprising an opening through one of said plates communicating with the other of said plates, and an impervious dam in said opening joining both of said abutting plates.

References Cited in the file of this patent UNITED STATES PATENTS 

